To fill the needs for touch panels in different applications, various touch control methods have been promoted. Among touch panels nowadays, capacitive touch panels have advantages of a high transparency, high hardness, short response time and a high sensitivity so they are widely applied to the touch control field.
Modern control methods for a capacitive touch panel can substantially be categorized into the active touch control method and the passive touch control method. The passive touch input method is carried out by using one or more fingers or a passive stylus pen to touch a touch panel; and an active touch input method is carried out by using an active stylus pen to touch a touch panel. As compared to a passive stylus pen, an active stylus pen can actively output signals in response to the actions of a capacitive touch panel so that it can do subtler actions, such as writing and painting on the capacitive touch panel.
However, modern active stylus pens support subtle actions but do not support the pressure sensing technology whereby a capacitive touch panel cannot display a trace having a different width according to the pen pressure. Therefore, it is necessary to develop an active stylus pen having the pressure sensing technology, and a signal transmission method between the active stylus pen and a capacitive touch panel, by which the capacitive touch panel can display a trace which has a different width according to the pen pressure and looks like a real brush stoke when the active stylus pen is used to write or paint on the capacitive touch panel.